Sample preparation and handling generally includes sample collection and any preprocessing required for subsequent biological and chemical assays. Sample collection and handling is an important part of in vitro diagnostic (IVD) testing, and is an important factor in determining the feasibility of test automation. With the advancement of medicine, the number of possible assays available to perform is continually increasing. In parallel, sample collection methods have evolved over the last several decades. In the case of blood sample collection, for example, disposable plastic syringes first replaced glass syringes to improve safety. Later developments had vacuum tubes replacing the traditional syringes to simplify the blood collection process. However, a vacuum tube is generally not suitable for use as an IVD test reaction chamber. Thus, a re-sampling process is necessary for delivery of the sample to distinct assay containers for each of a variety of IVD tests. Automation of these processes is a daunting task. Indeed, in large clinical testing centers giant automation testing systems costing several million dollars are currently used. The major automated task in these machines is liquid handling, which entails the pipetting of the sample from sample tubes to 96-well plates, the addition of the reagent(s) to the wells, as well as moving reaction mixtures from well to well.
Recently, nanotechnology has emerged to revolutionize automation and testing formats. In this direction, by using silicone micro-fabrication and etching technology, the lab-on-a-chip platform was developed in an attempt to integrate and miniaturize certain parts of the automation process into a chip with dimensions less than 2 mm by 2 mm. Liquid processing rates for certain lab-on-a-chip platforms can be on the scale of nanoliters per second. However, it is often difficult for users to interface with this type of platform to, for example, deliver the sample to the chip.
Another concern of current sample handling devices is the large sample volume routinely drawn from a patient for IVD testing. In the case of blood sample collection, for example, a small vacuum tube may take close to 5 ml whole blood. When multiple samples are required in the testing of various assays, several tubes of blood are frequently ordered. However, only a small amount is needed for each assay. The drawing of a large volume of blood for multiple tests is a concern for pediatric patients as it can lead to iron deficiency anemia. It is even more critical for patients with pre-existing anemia or a bleeding disorder.